This invention relates to the production of flame-retardant polyols. The inorganic-organic flame-retardant polyols are produced by mixing and reacting an epoxy compound, a compound containing one or more reactive hydrogen atoms that will react with an epoxy compound and an acidic boron compound in the presence of an epoxy catalyst. When this polyol is utilized in the production of polyurethane product the pH may need to be adjusted to where the pH is above 6. A basic salt-forming compound may be used to adjust the pH. When the flame-retardant polyol is to be utilized in the production of flame-retardant polyester polyols a polycarboxylic acid and/or polycarboxylic anhydride is added with the epoxy compound and after the reaction is partically completed further heating is required to complete the esterification.
While not wishing to be bound by any theory of operation, it appears that the acidic boron compound, epoxy compound, reactive hydrogen containing compound and certain epoxy catalyst react to produce an organic-inorganic flame-retardant polyol which may be further reacted with or in the presence of a basic salt forming compound to adjust the pH when necessary. An excess of the acidic boron compound may be used to further improve the flame-retardant properties. When phosphorus containing compounds are used as the epoxy catalyst further improvement in the flame-retardant properties is seen. The polyol produced may be further heated to esterify boric acid with an organic hydroxyl radical if desired. The low molecular weight polyol or unreacted epoxy compound may be separated by distillation from the higher molecular weight polyols and some of the low molecular weight polyols will also esterify with any free boron acid radicals present in the flame-retardant polyol which also assists in adjusting the pH to above 6.